2 Frequencies, brightness and beam-width

The effective frequencies and half-power beam-widths for the filters, and the brightness temperatures for the planets (except Mars) are read from the plain text files:

ukt14_old.dat

– for dates before 7-Aug-92.

ukt14.dat

– for the period 7-Aug-92 to 23-May-96.

scuba.dat

– for dates after 23-May-96.

scuba2.dat

– for dates after 1-Jan-2007.

The information in the files was supplied by the observatory. The differences mainly reflect changes in detector/telescope hardware.

The program selects the appropriate .dat file to use, based on the date you specify. The calculated temperature has an rms error of about 0.13K (negligible).

Alternatively, if the ADAM parameter “FILTER” is set to CUSTOM on the command line, then the the parameters of a single filter to use are obtained from the user using a set of environment parameters, rather than being read from a file as described above. The planetary brightness temperature can either be supplied explicitly or can be looked up from a specified NDF using the supplied frequency as the index (see parameter BTEMP below). For the case of Uranus, the FLUXES package includes two files that can be used for this purpose, both produced as part of the calibration effort for Herschel SPIRE spectroscopy:

esa2_uranus.sdf:

The initial Uranus model at Herschel launch.

esa4_uranus.sdf:

An updated model that includes Spitzer data for constraining the continuum, but no lines.

See Herschel Planetary Calibrator Models release notes for more information on these models.

The following parameters are used to describe the custom filter:

FREQ:

The central frequency of the filter in GHz.

NB:

The number of Gaussian components to the beam - must 1be 1 or 2.

HPBW1:

Half-power beam width of the first Gaussian component of the beam, in arcsec.

HPBW2:

Half-power beam width of the second Gaussian component of the beam, in arcsec. Unused if NB is 1.

AMP1:

Amplitude of the first Gaussian component of the beam, in arcsec, normalised so that AMP1 plus AMP2 is one. Unused if NB is 1.

AMP2:

Amplitude of the second Gaussian component of the beam, in arcsec, normalised so that AMP1 plus AMP2 is one. Unused if NB is 1.

BTEMP:

Either the numerical planetary brightness temperature at the required frequency, in K, or the name of a 1-dimensional NDF. If an NDF name is given, it should contain the required brightness temperature as a function of frequency. The current WCS Frame should contain a spectral axis giving frerquency in units of GHz. The NDF is used to look up the required temperature at the frequency specified by parameter FREQ. Note, this parameter is not used if Mars is the selected planet (see appendix B.3 for a description of the brightness temperature used for Mars).

NOTE:

A group of lines of explanatory text to display. Defaults to none.

Bear in mind that Saturn can only be used for calibration when the rings are not open, and the Martian brightness temperatures are probably only accurate to around $\pm 5$%.